How Battles Work
Battles occur when you are at war and your army meet an enemy army in the same region. They will clash to become a battle. The battle will be fought in three (3) phases; the maneuver, the main phase, and the aftermath.
The maneuver phase happens at the beginning of the battle and indicates the time it will take before the battle truly begins. The main phase is when the actual fighting happens and is where the soldiers, knights, etc. meet on the battlefield. The main phase will end when one side becomes casualties or have decided to retreat off the battlefield. The last phase is the aftermath phase where the victor of the battle will rundown as many soldiers as possible.
Once your army is in a battle you will be able to see all the advantages that your army has in the battle and also the advantages that the enemy army has as well. For example your commander’s martial skill can give you a huge advantage over your opponent. Martial ability is how good a character is at leading armies into battle and waging war.
Terrain is also a key component when it comes to battles. In Crusader Kings 3 you can hover over regions and see what terrain type they are and use that against your enemy. For example the region of Tralee is a Wetland. With that in mind you could use that as a defensive advantage against an attacking enemy.
Knights are also an important element to your medieval army. Knights are nobles that join your army to fight alongside your soldiers. During battles the knights use the prowess skill, which is an indicator of how much damage they will inflict on the enemies and how likely they are to survive the battle. The higher the prowess skill the better. You can also improve your knights through your ruler’s knight effectiveness.
Battles can be very unpredictable and to simulate that in Crusader Kings 3, there are dice rolls. Every three (3) days of battle dice are rolled ranging from 0 to 10, although traits can modify that range. Each point of advantage that one side has over the other increases the damage output by 2%.
Wars are not all fought in pitch battles, but sieges as well. Sieges happen when an army surrounds a fortified holding. Depending on the fort level, the number of garrisoned units, and the size of the attacking army sieges can last a long time. As you starve out your enemies you will see be able to see the progress through the siege HUD and see how long the siege is going to take. Keep in mind if you have a much larger army relative to the garrisoned force or your army is equipped with siege equipment the siege process will be much faster. This is ideal if you have a lot of holdings to capture.
Whether you are attacking or defending you will want to pay attention to rivers and river crossings. Rivers give defensive armies a huge advantage over an attacking army. In fact if you find yourself greatly outnumbered it might be best for your army to hold a river. It can turn a likely defeat into an amazing victory.